Trong một dân số lớn phẫu thuật nói chung 68% (16/11) của các sự kiện thuyên tắc huyết khối xảy ra ở những bệnh nhân đã được phẫu thuật vì một khoảng thời gian cần thiết để không tiếp tục kháng đông trước khi phẫu thuật tim không phụ thuộc vào: thời gian bán hủy | ANTICOAGULATION IN VALVAR HEART DISEASE Table Risk assessment for non-cardiac surgical procedures Low High According to risk factors related to risk risk Patients Atrial fibrillation Previous thromboembolism Hypercoagulable congenital or acquired conditions Left ventricular dysfunction Heart failure Prostheses design Ball valve Tilting disk Bileaflet Prostheses position Aortic Mitral Procedures Dental ophthalmic Skin Gastrointestinal Pathology Tumour Infection Different management strategies have been suggested including discontinuation of oral anticoagulation until normalisation of the INR without heparin replacement discontinuation of oral anticoagulation until normalisation of the INR with heparin replacement as soon as the INRis lowering the intensity of anticoagulation while oral anticoagulation is maintained continuing a therapeutic level of anticoagulation. The choice of which regimen should be followed should be based on the individual risk for thromboembolic events the time interval required to be off or at low anticoagulation levels and the risk of haemorrhage determined by the procedure. Thus the concept of risk factor adjusted intensity of anticoagulation can also be used to determine the most appropriate and safest strategy. Patient related risk factors table increase thromboembolic risk by a factor of 5 20. Also prosthesis design and position have to be taken into account. Discontinuation of anticoagulation for one week leads to a signi -cant thromboembolic risk in patients with mitral valve replacement varying between 10 20 whereas the incidence of thromboembolism in patients with aortic valve replacement is 0 2 .12 w9 w14 The prothrombotic state of the surgical procedure itself may increase the risk for thromboembolic events. All stages of haemostasis can be altered during and after surgery with increased platelet aggregation and activation conversion of fibrinogen to fibrin and depressed fibrinolysis by decreased activators and .
